The methods and systems of the present invention are directed to the modification and improvement of transmissions for automotive vehicles of the type installed by original equipment manufacturers. Such transmissions, are commonly referred to as xe2x80x9cfactory installedxe2x80x9d, and this terminology will be adopted in the following discussion. The invention is particularly directed to the improvement and modification of automotive transmissions commonly known as TFOD-DSL which are installed in vehicles produced by Chrysler Motor Corporation, RE4R01A installed in vehicles produced by Mazda Motors Corporation, and 4R44E/4R55E installed in vehicles produced by the Ford Motor Corporation.
The present inventor owns U.S. Pat. No. 4,449,426 issued on May 22, 1984; U.S. Pat. No. 4,711,140, issued on Dec. 8, 1987; U.S. Pat. No. 4,790,938, issued on Dec. 13, 1988; U.S. Pat. No. 5,253,549, issued on Oct. 19, 1993; U.S. Pat. No. 5,540,628, issued on Jul. 30, 1996; U.S. Pat. No. 5,624,342, issued on Apr. 29, 1997; U.S. Pat. No. 5,730,685, issued on Mar. 24, 1998; U.S. Pat. No. 5,743,823, issued on Apr. 28, 1998; U.S. Pat. No. 5,768,953 issued on Jun. 23, 1998; U.S. Pat. No. 5,820,507 issued on Oct. 13, 1998; U.S. Pat. No. 5,967,928 issued on Oct. 19, 1999; U.S. Pat. No. 6,099,429 issued on Aug. 8, 2000; U.S. Pat. No. 6,117,047 issued on Sep. 12, 2000. The disclosures of these patents are expressly incorporated by reference herein.
In the factory installed TFOD-DSL automotive transmission, Applicant has recognized that when this transmission is subjected to severe operating conditions, it lacks the necessary torque capacity to prevent slipping of gears. Although an increase in mainline pressure will correct the slipping, merely increasing the line pressure will result in undesirable side effects such as late shifting or no upshifting under wide open throttle conditions.
With regard to the factory installed RE4R01A automotive transmission, Applicant has recognized that modification of the hydraulic circuitry of this transmission can extend the range of accumulator pressure from about 70 psi to 150 psi or greater. Extending the range of accumulator pressure will result in improvement to the quality of the xe2x80x9c1-2xe2x80x9d shift and also will extend the operating life of the transmission. Applicant has also recognized that the seal assembly of the RE4R01A automotive transmission is arranged in a manner in which leakage of transmission fluid can occur during operation of the transmission resulting in clutch plate slippage which adversely affects the operation of the transmission.
With regard to the 4R44E/4R55E automotive transmission, Applicant has recognized that forward movement of the vehicle relies upon several different cooperating components including a power train control module, an EPC (electronic pressure control) solenoid for regulating pressure, and the ability of a forward modulator valve to regulate a forward engagement control valve. The failure of any of these components of this automotive transmission can result in loss of forward movement of the vehicle.
It is the object of the present invention to eliminate the aforementioned disadvantages of the known factory installed automotive transmissions. In particular, the primary objects of the present invention include increasing the main line pressure of the factory installed TFOD-DSL automotive transmission without resulting in the undesireable side effects including late shifts and no upshifts during wide open throttle conditions; modifying the hydraulic circuitry of the factory installed RE4R01A is automotive transmission to extend the range of accumulator pressure from 70 psi to 150 psi or greater for improving the quality of the xe2x80x9c1-2xe2x80x9d shift and for extending the useful life of the automotive transmission; improving the sealing assembly of the factory installed RE4R01A automotive transmission to prevent leakage of fluid and slippage and burnout of the clutch plate; modifying the hydraulic circuitry of the factory installed 4R44E/4R55E automotive transmission for providing a smooth, quick and positive forward clutch apply circuit that is reliable and controlled exclusively by movement of the shift control lever, and increasing the servo apply pressure to the intermediate and overdrive servos for increasing the holding capacity of the second and fourth gear bands and for providing means for adjusting the feel of the shift (e.g., softer or firmer) to suit the needs of a particular driver or vehicle.
Other objects and advantages of the present invention will become apparent to those skilled in the art from the following discussion.
In a first aspect of the present invention, a factory installed TFOD-DSL automotive transmission is modified to increase the main line pressure from a maximum of approximately 95 psi to 120 psi or greater by replacing the original pressure regulator spring to exert an increased resilient force on the pressure regulator valve. The regulator valve feeds main line pressure to the throttle valve, and when the throttle valve is opened mechanically, the throttle pressure corresponds to the main line pressure. By increasing the resilient force applied by the pressure regulator spring to the pressure regulator valve, the throttle pressure is increased, thereby increasing main line pressure. Increasing the main line pressure increases the torque capacity of the transmission which tends to prevent slipping of gears and soft shifts. However, in order to avoid undesirable side effects of increased pressure including late shifts or no upshift during wide open throttle, the size of the throttle valve is adjusted (decreased) to avoid direct contact between the throttle valve and a kickdown valve at above approximately 7/8th of wide open throttle operation. By avoiding direct contact between the kickdown valve and the throttle valve above 7/8th throttle condition, the throttle. valve is not opened mechanically by the kickdown valve, but instead, the throttle valve spring continues to regulate both the throttle pressure and the corresponding main line pressure through wide open throttle. In this manner, the undesirable side effects of increased main-line pressure, including late shifts and no upshift at wide open throttle, are avoided.
In a further embodiment of the present invention, the hydraulic circuitry of the factory installed RE4R01A automotive transmission is modified to increase the accumulator pressure from approximately 70 psi to approximately 150 psi or greater. Extending the pressure range of the accumulator results in a better quality of shift of the 1-2 shift valve and extends the useful life of the transmission including the second gear bands.
In a further embodiment of the present invention, the sealing assembly of the factory installed RE4R01A automotive transmission is modified to prevent leakage and extend the useful life of the seal. The modification to the factory installed sealing system includes mounting a wire retaining element around the outer surface of a seal element mounted around the outer surface of a rotatable shaft to increase the inwardly directed force applied to the seal pressing it against the shaft, and to counteract centrifugal forces applied to the seal tending to displace the seal away from the shaft as the shaft rotates.
In a further embodiment of the present invention, the hydraulic circuitry of a factory installed 4R44E/4R55E automotive transmission is modified to provide a smooth, quick and forward clutch apply circuit that is reliable and is controlled exclusively by movement of the shift control lever and not by the power train control module, the EPC regulating solenoid, the availability of the forward modulator valve to regulate a forward engagement control valve, or the ability of a forward clutch circuit to rapidly attain a pressure of 40 psi. The hydraulic circuitry of the factory installed 4R44E/4R55E automotive transmission is further modified to increase servo apply pressure to the intermediate and overdrive servos for increasing the holding capacity of the second and fourth gear bands and to provide means for adjusting the feel of the shift (e.g., soft or firm) to suit a particular driver or vehicle, as desired.